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The development and continuity of consistent long-term data records from similar overlapping satellite observations is critical for global monitoring and environmental change assessments. We developed an empirical approach for inter-calibration of satellite microwave brightness temperature (Tb) records over land from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and Microwave Scanning Radiometer 2 (AMSR2) using overlapping Tb observations from the Microwave Radiation Imager (MWRI). Double Differencing (DD) calculations revealed significant AMSR2 and MWRI biases relative to AMSR-E. Pixel-wise linear relationships were established from overlapping Tb records and used for calibrating MWRI and AMSR2 records to the AMSR-E baseline. The integrated multi-sensor Tb record was largely consistent over the major global vegetation and climate zones; sensor biases were generally well calibrated, though residual Tb differences inherent to different sensor configurations were still present. Daily surface air temperature estimates from the calibrated AMSR2 Tb inputs also showed favorable accuracy against independent measurements from 142 global weather stations (R2 ≥ 0.75, RMSE ≤ 3.64 °C), but with slightly lower accuracy than the AMSR-E baseline (R2 ≥ 0.78, RMSE ≤ 3.46 °C). The proposed method is promising for generating consistent, uninterrupted global land parameter records spanning the AMSR-E and continuing AMSR2 missions. [ABSTRACT FROM AUTHOR]

Application of sensor-based technology within activity monitoring systems is becoming a popular technique within the smart environment paradigm. Nevertheless, the use of such an approach generates complex constructs of data, which subsequently requires the use of intricate activity recognition techniques to automatically infer the underlying activity. This paper explores a cluster-based ensemble method as a new solution for the purposes of activity recognition within smart environments. With this approach activities are modelled as collections of clusters built on different subsets of features. A classification process is performed by assigning a new instance to its closest cluster from each collection. Two different sensor data representations have been investigated, namely numeric and binary. Following the evaluation of the proposed methodology it has been demonstrated that the cluster-based ensemble method can be successfully applied as a viable option for activity recognition. Results following exposure to data collected from a range of activities indicated that the ensemble method had the ability to perform with accuracies of 94.2% and 97.5% for numeric and binary data, respectively. These results outperformed a range of single classifiers considered as benchmarks. [ABSTRACT FROM AUTHOR]

Solid-state incandescent light-emission devices (SSI-LEDs) with a metal-oxide-semiconductor structure are promising candidates for future broadband light-emission devices. In this work, the electrical and light-emission features of SSI-LEDs based on HfO2 high-k thin films with or without the Ti-embedded layer on p-type silicon wafers have been studied. It turns out that the Ti-embedded layer can effectively reduce the turn-on voltage, thus improving the fluorescence efficiency of SSI-LEDs. The combination of scanning electron microscopy, atomic force microscope (AFM) and conductive AFM results unambiguously clarifies that conductive filaments, which are formed due to local thermal excitation during the forming process, are accompanied by the formation of pits on the HfO2 surface and are responsible for the light emission. This work develops an effective approach to improving the luminescence performance of SSI-LEDs and experimentally explains the light-emitting mechanism of such devices, which is of great importance to eventually realizng broadband light-emitting devices with low power consumption. [ABSTRACT FROM AUTHOR]

Propagation of a signal beam in an AlGaAs/GaAs waveguide multiple-prism light deflector is theoretically investigated by solving the scalar Helmholtz equation to obtain the dependences of the temporal and spatial resolvable characteristics of the ultrafast deflector on the material dispersion of GaAs including group velocity dispersion and angular dispersion, interface reflection, and interface scattering of multiple-prism deflector. Furthermore, we experimentally confirm that, in this ultrafast beam deflection device, the deflecting angle of the signal light beam is linear with the pump fluence and the temporal resolution of the ultrafast deflection is 10 ps. Our results show that the improvement of the temporal and spatial resolvable performances is possible by properly choosing the structural parameters and enhancing the quality of the device. [ABSTRACT FROM AUTHOR]

Introduction. In the big data age, we have to deal with a tremendous amount of information, which can be collected from various types of sources. For information search systems such as Web search engines or online digital libraries, the collection of documents becomes larger and larger. For some queries, an information search system needs to retrieve a large number of documents. On the other hand, very often people are only willing to visit no more than a few top-ranked documents. Therefore, how to develop an information search system with desirable efficiency and effectiveness is a research problem. Method. In this paper, we focus on the data fusion approach to information search, in which each component search model contributes a result and all the results are combined by a fusion algorithm. Through empirical study, we are able to find a feasible combination method that balances effectiveness and efficiency in the context of data fusion. Analysis. It is a multi-optimisation problem that aims to balance effectiveness and efficiency. To support this, we need to understand how these two factors affect each other and to what extent. Results. Using some groups of historical runs from TREC to carry out the experiment, we find that using much less information (e.g., less than 10% of the documents in the experiment), good efficiency is achievable with marginal loss on effectiveness. Conclusions. We consider that the findings from our experiment are informative and this can be used as a guideline for providing more efficient search service in the big data environment. [ABSTRACT FROM AUTHOR]

A simulation model was built to numerically investigate the electron emission property of a new surface-conduction electron emitter (SCE) with a raised emitter structure. The model calculated the electric field distribution, the electron emission characteristics, and the electron trajectories, which were useful for analyzing and understanding the microscopic mechanism of the electron emissions of the new SCE structure. It was found that the new structure increased the probability of electrons being collected by the anode which led to an increase of the anode current despite of the decrease of field emission current. This study benefits the advanced design of emitter structures in nanoscale technology for new types of electron sources. [ABSTRACT FROM AUTHOR]

Accurate long-term daily Cloud-gap-filled fractional snow cover products are essential for climate change and snow hydrological studies in the Asia Water Tower (AWT) region, but existing Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products are not sufficient. In this study, the multiple endmember spectral mixture analysis algorithm based on automatic endmember extraction (MESMA-AGE) and the multistep spatiotemporal interpolation algorithm (MSTI) are used to produce the MODIS daily cloud-gap-filled fractional snow cover product over the AWT region (AWT MODIS FSC). The AWT MODIS FSC product have a spatial resolution of 0.005°, and spans from 2000 to 2022. The 2745 scenes of Landsat-8 images are used for the areal scale accuracy assessment. The fractional snow cover accuracy metrics, including coefficient of determination (R2 ), root mean squared error (RMSE), and mean absolute error (MAE) are 0.80, 0.16 and 0.10, respectively. The binarized identification accuracy metrics, including overall accuracy (OA), producer’s accuracy (PA), and user’s accuracy (UA), are 95.17%, 97.34% and 97.59%, respectively. Snow depth data observed at 175 meteorological stations are used to evaluate accuracy at point scale, yielding the following accuracy metrics: an OA of 93.26%, a PA of 84.41%, a UA of 82.14%, and a cohen’s kappa (CK) value of 0.79. Snow depth observations from meteorological stations are also used to assess the fractional snow cover resulting from different weather conditions, with an OA of 95.36% (88.96%), a PA of 87.75% (82.26%), a UA of 86.86% (78.86%) and a CK of 0.84 (0.72) under the MODIS clear sky observations (spatiotemporal reconstruction based on the MSTI algorithm). The AWT MODIS FSC product can provide quantitative spatial distribution information of snowpack for mountain hydrological models, land surface models, and numerical weather prediction in the Asia Water Tower region. [ABSTRACT FROM AUTHOR]

Sea ice concentration (SIC) is the main variable for quantifying the sea ice change in the polar regions. Continuous SIC data is very important for the studies of climate and polar marine environments. This study generates a new SIC product covering the Arctic and Antarctic from November 2010 to December 2019. It is the first long-term SIC product derived from the Microwave Radiation Imager (MWRI) sensors onboard the Chinese FengYun-3B, -3C, and -3D satellites, after a recent re-calibration of brightness temperature. We also modified the preliminary dynamic tie points Arctic Radiation and Turbulence Interaction Study Sea Ice (ASI) algorithm mainly through input TB and initial tie points. The MWRI-ASI SIC was compared to the existing ASI SIC products and validated using ship-based SIC observations. Results show that the MWRI-ASI SIC mostly coincides with the ASI SIC obtained from the Special Sensor Microwave Imager series sensors, with overall biases of -1.4 ± 1.8% in the Arctic and 0.5 ± 2.2% in the Antarctic, respectively. The overall mean absolute deviation between the MWRI-ASI SIC and ship-based SIC is 16.1% and 17.1% in the Arctic and Antarctic, respectively, which is close to the existing ASI SIC products. The trend of sea ice extent (SIE) derived from MWRI-ASI SIC closely agrees with those of the Sea Ice Index SIEs provided by OSI-SAF and NSIDC. Therefore, the MWRI-ASI SIC is comparable with other SIC products and is qualified to be integrated into long-term sea ice records. The MWRI-ASI SIC dataset is available at https://doi.pangaea.de/10.1594/PANGAEA.945188 (Chen et al., 2022). [ABSTRACT FROM AUTHOR]

Background: Many studies demonstrate a J-shaped association between blood pressure and cardiovascular diseases (CVDs), but the findings are plagued by confounding from other traditional cardiovascular risk factors (CVRFs). Our aims were to examine the associations of systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels with CVD in individuals without major CVRFs and whether there were thresholds for the association., Methods: In the 4C study (China Cardiometabolic Disease and Cancer Cohort), 36 042 CVRF-free participants without CVD, diabetes, dyslipidemia, hypertension, or smoking were identified during 2011 to 2012. Among CVRF-free participants, 17 476 CVRF-preferable individuals with better glycemic (fasting glucose, <110 mg/dL; 2-hour post-load glucose, <140 mg/dL) and lipid profile (total cholesterol, <200 mg/dL; LDL [low-density lipoprotein] cholesterol, <130 mg/dL) were selected. The total person-years of follow-up for CVRF-free subjects and CVRF-preferable subjects were 130 147 and 63 573 person-years, respectively. Information on the development of major CVDs was collected during 2014 to 2016. Cox proportional hazard models were performed to estimate the risks for incident CVD by SBP and DBP groups, respectively., Results: We found that both baseline SBP and DBP presented significantly linear associations with CVD risks in CVRF-free and CVRF-preferable participants. There is significant increase in the CVD risk among CVRF-free participants with baseline SBP level of 110 to 119 mm Hg (hazard ratio, 1.79 [95% CI, 1.19-2.71]), 120 to 129 mm Hg (hazard ratio, 2.03 [95% CI, 1.36-3.03]), and 130 to 139 mm Hg (hazard ratio, 2.15 [95% CI, 1.40-3.28]) compared with SBP <110 mm Hg. Significant increases were also observed for DBP level of 80 to 89 mm Hg (hazard ratio, 1.43 [95% CI, 1.03-1.97]) compared with DBP <70 mm Hg. Similar results were observed in CVRF-preferable participants., Conclusions: SBP and DBP with levels currently considered normal were significantly and linearly associated with incident CVD without thresholds above 110/70 mm Hg among Chinese adults without major CVRFs.